In, for example, a machining center or other NC machine tool, when working a workpiece, a tool such as a drill bit or end mill which is attached to the spindle is made to rotate while contacting the workpiece. In raising the precision of positional control of the tool, the position of the tool with respect to the spindle, heat deformation of the rotating spindle, etc. must be considered. Therefore, it is important to actually measure in advance the dimensions of the tool which is attached to the spindle.
PLT 1: Japanese Patent No. 3880110
PLT 2: Japanese Patent Publication No. 9-83843A
PLT 3: Japanese Patent Publication No. 2007-326196A
PLT 4: Japanese Patent Publication No. 2007-49489A